1. Field of the Invention
This invention is directed to novel water soluble, methacrylic ester, quaternary ammonium, cross-linking monomers and to their synthesis; and in particular to the use of the same in the manufacture of novel anion exchange resins or polymers using an aqueous solvent system.
2. Description of the Prior Art
The usual technique for the production of ion-exchange polymers involves polymerizing a non-ionic, non-water soluble, cross-linking agent, as for example, divinyl benzene with a monomer such as vinylbenzyl chloride in a non-aqueous solvent such as diethylbenzene. The resulting solid polymer, for example, in sheet or membrane form is equilibrated or washed several times with a water soluble solvent such as methanol so as to remove and replace the diethylbenzene solvent which is hydrophobic. Where anion exchangers are desired the membranes are then reacted with an aqueous solution of an amine such as trimethylamine to form quaternary ammonium chloride groups which gives the polymer its strongly basic ion-exchange properties. The prior art has disadvantages in that the cross-linking agent is non-ionic thus producing polymers having low ion-exchange capacity. Further, the monomers employed are water insoluble and the polymerization reaction is carried out in a non-aqueous solvent system. This requires replacing the petroleum-derived solvents in the polymer with an aqueous solvent; thus necessitating a disposal problem with loss of the organic solvents.
The present invention comprises an improvement over the methods of the prior art by providing water soluble monomers polymerized in an aqueous solvent system employing an ionically active, cross-linking agent. Thus ion-exchange polymeric membranes are prepared having high ion-exchange capacities and low electrical resistance. Additionally the polymerization step requires shorter time periods and lower curing temperatures for a net saving in energy. Also the expense of petroleum derived solvents and the problem of their disposal is eliminated.